In recent years, a wireless communication module has been used in a wireless communication device, a radar device, and an imaging device using a high-frequency electromagnetic wave (high frequency signal) in, for example, a millimeter wave band or higher. The wireless communication module includes, for example, a waveguide horn antenna (horn antenna) and a semiconductor chip (Monolithic Microwave Integrated Circuit (MMIC)).
For example, a horn antenna used in a wireless communication device or the like transmits and receives a high frequency signal, includes a truncated pyramidal (conical) metal waveguide whose port is tapered in a manner to be gradually widened, has good beam pattern controllability, and is capable of earning a high antenna gain. Note that the term “high frequency signal” herein includes, for example, a signal of a millimeter wave (wavelength from 1 mm to 10 mm: frequency from 30 GHz to 300 GHz), a sub-millimeter wave (1 mm or less: 300 GHz or more), and a terahertz wave (30 μm to 3 mm: 0.1 THz to 10 THz).
In a wireless communication module, for example, a high frequency signal transmitted and received by a horn antenna is processed by a semiconductor chip (MMIC). When a high frequency signal is input, for example, a propagation mode of the high frequency signal is converted from a signal for a horn antenna (waveguide) to a signal for a planar transmission line (microstrip line) and is input to a semiconductor chip. In addition, when a high frequency signal is output, for example, a signal from the semiconductor chip via the planar transmission line is converted into a propagation mode for a high frequency signal and is output from the horn antenna. In this manner, a wireless communication module (extremely high frequency band module) includes, mounted thereon, a horn antenna, an antenna conversion unit, a substrate for signal transmission and a semiconductor chip, for example.
In addition, it has been recently contemplated that a wireless communication module is mounted on a compact portable terminal such as a smartphone and a wearable device. However, since the wireless communication module includes a horn antenna, size reduction, in particular, thickness reduction is desired.
Specifically, for example, a wireless communication module with a thickness (height) of 1 mm or less is desired to be mounted on a smartphone or the like without deteriorating design flexibility. The problem in size is present not only when mounting a wireless communication module on a compact portable terminal such as a smartphone but also when applying a wireless communication module to various devices.
Incidentally, in the past, there have been proposed various wireless communication modules to which a waveguide horn antenna is applied.
Patent Document 1: Japanese Laid-open Patent Publication No. 2014-179935
Patent Document 2: Japanese Laid-open Patent Publication No. 2013-247494
Patent Document 3: Japanese Laid-open Patent Publication No. 1998(H10)-224141
Patent Document 4: Japanese Laid-open Patent Publication No. 2002-353729